Level reward choice values per ManteoMax Forza 4 spreadsheet. This is similar to OutlawMustang's solution but lists choices in decreasing value and includes DLC choices. Asterisks (*) refer to cars given as rewards in original release but may have been removed from reward choices.
ManteoMax posted his version of this list at the FM forums which includes car class & PI;
http://forums.forzamotorsport.net/turn10_postsm14840_Driver-...ManteoMax's Forza 4 spreadsheet contains any stat you'd want to sort on:
http://manteomax.com/Level 1 Reward Choices2010 Fiat Punto Evo SPORT (20,000 credits)
2009 Ford Fiesta Zetec S (19,000 credits)
2011 Mazda 2 (14,000 credits)
2011 Suzuki SX4 Sportback (14,000 credits)
2009 Honda Fit Sport (12,000 credits)
2009 Scion xD (11,000 credits)
2008 Toyota Yaris S (10,000 credits)
Level 2 Reward Choices1994 Mazda MX-5 Miata (Gen 1) (7,000 credits)
1994 Nissan 240SX SE (7,000 credits)
1989 Toyota MR2 SC (6,000 credits)
1992 Volkswagen Golf GTi 16v Mk2 (6,000 credits)
1994 Honda Civic 1.5 VTi (5,000 credits)
Level 3 Reward Choices1965 Alfa Romeo Giulia Sprint GTA Stradale (60,000 credits)
1971 Lotus Elan Sprint (30,000 credits)
1973 BMW 2002 Turbo (28,000 credits)
1971 Nissan Skyline 2000GT-R (28,000 credits)
1969 Nissan Fairlady Z 432 (12,000 credits)
Level 4 Reward Choices2011 Citroen DS3 (24,000 credits)
2010 Mitsubishi Colt Ralliart (22,000 credits)
2008 Alfa Romeo MiTo (20,000 credits)
2009 SEAT Ibiza CUPRA (17,000 credits)
2009 Renault Twingo Renault Sport Cup (16,000 credits)
Level 5 Reward Choices1960 Chevrolet Corvette C1 (80,000 credits)
1966 Chevrolet Nova SS (78,000 credits, 2011.10 Muscle DLC)
1957 Ford Thunderbird (60,000 credits)
1965 Pontiac GTO (44,000 credits, 2011.10 Muscle DLC)
1965 Ford Mustang GT Coupe (26,000 credits, 2012.01 Launch DLC)
Level 6 Reward Choices1970 Ford Mustang Boss 429 (120,000 credits)
1970 Mercury Cougar Eliminator (48,000 credits)
1969 Pontiac Firebird Trans Am (45,000 credits)
1971 AMC Javelin-AMX (20,000 credits)
1969 Chevrolet Camaro Z28 (12,000 credits)
Level 7 Reward Choices1992 Nissan Silvia CLUB K's (S13) (6,000 credits)
1985 Toyota Sprinter Trueno GT Apex (6,000 credits)
1988 Mitsubishi Starion ESI-R (5,000 credits)
Level 8 Reward Choices1969 Shelby GT500 428CJ (110,000 credits, 2011.10 Muscle DLC)
1973 Ford XB Falcon GT (50,000 credits)
1971 Ford Mustang Mach 1 (40,000 credits)
Level 9 Reward Choices1970 Dodge Coronet Super Bee (250,000 credits, 2011.10 Muscle DLC)
1971 Plymouth GTX 426 Hemi (125,000 credits, 2011.10 Muscle DLC)
1970 Chevrolet Chevelle SS-454 (48,000 credits)
1969 Pontiac GTO Judge (44,000 credits)
1969 Oldsmobile Hurst/Olds 442 (40,000 credits)
Level 10 Reward Choices2011 Alfa Romeo Giulietta Quadrifoglio Verde (36,000 credits, 2012.01 Launch DLC)
2010 Peugeot RCZ (34,000 credits)
2009 Volkswagen Scirocco GT (32,000 credits)
2013 Hyundai Veloster Turbo (22,000 credits, 2012.01 Veloster DLC)
2010 Mazda Mazdaspeed 3 (17,000 credits)
Level 11 Reward Choices1982 Lancia 037 Stradale (240,000 credits)
1980 Renault 5 Turbo (38,000 credits)
1992 Ford Escort RS Cosworth (24,000 credits)
1992 Lancia Delta Integrale EVO (22,000 credits)
1994 Toyota Celica GT-Four ST205 (9,000 credits)
Level 12 Reward Choices1987 Ford Sierra Cosworth RS500 (52,000 credits)
1990 Mercedes 190E 2.5-16 Evolution II (26,000 credits)
1991 BMW M3 E30 (16,000 credits)
Level 13 Reward Choices2009 Audi Q7 V12 TDI (100,000 credits)
2008 Land Rover Range Rover Supercharged (68,000 credits)
2008 Volkswagen Touareg R50 (65,000 credits)
2009 Jeep Grand Cherokee SRT8 (36,000 credits)
2006 Dodge Ram SRT10 (24,000 credits)
Level 14 Reward Choices2000 Nissan Silvia Spec-R (S15) (16,000 credits)
1997 Honda Civic Type R (9,000 credits)
2000 Honda Integra Type-R (8,000 credits)
1995 Toyota MR2 GT (7,000 credits)
1995 Mitsubishi Eclipse GSX (6,000 credits)
Level 15 Reward Choices1968 Dodge Dart HEMI Super Stock (350,000 credits, 2011.10 Muscle DLC)
1964 Ford Fairlane Thunderbolt (200,000 credits, 2011.10 Muscle DLC)
1971 Plymouth Cuda 426 HEMI (120,000 credits)
1967 Chevrolet Corvette Stingray 427 (C2) (90,000 credits)
1969 Chevrolet Nova SS 396 (55,000 credits, 2012.03 Pirelli DLC)
Level 16 Reward Choices1967 Lamborghini Miura P400 (400,000 credits)
1968 Ferrari 365 GTB/4 (270,000 credits)
1971 De Tomaso Pantera (45,000 credits)
Level 17 Reward Choices2004 Opel Speedster Turbo (35,000 credits)
2005 Lotus Elise 111S (21,000 credits)
2004 Vauxhall VX220 Turbo (20,000 credits)
Level 18 Reward Choices1998 Subaru Impreza 22B STi (35,000 credits)
2011 Subaru WRX STI (32,000 credits, 2012.01 Launch DLC)
2008 Mitsubishi Lancer Evolution X GSR (29,000 credits)
2008 Subaru Impreza WRX STi (25,000 credits)
1999 Mitsubishi Lancer Evolution VI GSR (12,000 credits)
Level 19 Reward Choices2011 Audi RS3 Sportback (60,000 credits, 2011.11 Speed DLC)
2010 Honda Mugen Civic Type-R 3D (55,000 credits)
2010 Volkswagen Golf R (Mk6) (42,000 credits)
2009 Ford Focus RS (38,000 credits)
2013 Ford Focus ST (32,000 credits, 2011.11 Speed DLC)
* 2010 Renault Megane RS 250 (29,000 credits)
* 2010 SEAT Leon CUPRA R (24,000 credits)
Level 20 Reward Choices1992 Honda NSX-R (90,000 credits)
1998 Toyota Supra RZ (28,000 credits)
1997 Mazda RX-7 (FD) (18,000 credits)
1997 Nissan Skyline GT-R V-Spec (R33) (18,000 credits)
1997 Mitsubishi GTO (8,000 credits)
Level 21 Reward Choices2010 Ford Shelby GT500 (48,000 credits)
2012 Dodge Charger SRT8 (38,000 credits, 2011.11 Speed DLC)
2009 Dodge Challenger SRT8 (38,000 credits)
2010 Chevrolet Camaro SS (36,000 credits)
Level 22 Reward Choices2009 Holden HSV w427 (110,000 credits)
2010 Mercedes C63 AMG (60,000 credits)
2009 Lexus IS F (51,000 credits)
2010 Audi S4 (46,000 credits)
Level 23 Reward Choices2010 Mercedes SLK 55 AMG (58,000 credits)
2010 Chevrolet Corvette Grand Sport (C6) (55,000 credits)
2008 BMW M3 E92 (52,000 credits)
2007 Audi S5 (42,000 credits)
2010 Nissan 370Z (34,000 credits)
Level 24 Reward Choices2009 Audi RS 6 (140,000 credits)
2010 Mercedes E 63 AMG (100,000 credits)
2012 BMW M5 F10 (90,000 credits, 2011.10 BMW DLC)
2010 Jaguar XFR (80,000 credits)
2009 Cadillac CTS-V (58,000 credits)
Level 25 Reward Choices1984 Ferrari GTO (288) (320,000 credits)
1988 Lamborghini Countach LP5000 QV (150,000 credits)
Level 26 Reward Choices2010 Spyker C8 Laviolette LM85 (250,000 credits)
2010 Morgan Aero SuperSports (160,000 credits)
2005 TVR Sagaris (56,000 credits)
Level 27 Reward Choices2008 Aston Martin DBS (250,000 credits)
2010 Bentley Continental Supersports (250,000 credits)
2010 Mercedes CL 65 AMG (200,000 credits)
2011 Audi RS 5 (105,000 credits, 2012.01 Jalopnik DLC)
2010 BMW M6 Coupe (95,000 credits)
Level 28 Reward Choices2004 Ferrari F430 (150,000 credits)
2005 Ford Ford GT (150,000 credits)
2005 Aston Martin DB9 Coupe (130,000 credits)
2006 Chevrolet Corvette Z06 (C6) (48,000 credits)
2003 Dodge Viper SRT-10 (42,000 credits)
Level 29 Reward Choices2009 Mercedes SL 65 AMG Black Series (280,000 credits)
2010 Aston Martin V12 Vantage (270,000 credits)
2009 Jaguar XKR-S (100,000 credits)
Level 30 Reward Choices1967 Ferrari 330 P4 (9,000,000 credits)
1965 Shelby Cobra Daytona Coupe (5,000,000 credits)
1966 Ford GT40 MKII (1,500,000 credits)
Level 31 Reward Choices1993 McLaren F1 (3,000,000 credits)
1995 Ferrari F50 (400,000 credits)
1992 Bugatti EB110 SS (300,000 credits)
1993 Jaguar XJ220 (180,000 credits)
2010 Nissan GT-R SPECV (150,000 credits)
Level 32 Reward Choices2009 Chevrolet Corvette ZR1 (100,000 credits)
2008 Dodge Viper SRT10 ACR (100,000 credits)
Level 33 Reward Choices2009 Mercedes SLR Stirling Moss (1,000,000 credits)
2006 Lamborghini Miura Concept (420,000 credits)
2010 Saleen S5S Raptor (180,000 credits)
Level 34 Reward Choices2011 RUF Rt 12 S (270,000 credits)
2010 Ferrari 458 Italia (240,000 credits)
2011 McLaren MP4-12C (220,000 credits)
2010 Audi R8 5.2 FSI quattro (150,000 credits)
2005 Lamborghini Gallardo (110,000 credits)
Level 35 Reward Choices2010 Bertone Mantide (1,000,000 credits)
2010 Spada Codatronca TS (400,000 credits)
2010 Devon GTX (300,000 credits)
2010 Wiesmann GT MF5 (220,000 credits)
2010 Rossion Q1 (120,000 credits)
Level 36 Reward Choices2010 Aston Martin One - 77 (1,800,000 credits)
2011 Ferrari 599 GTO (370,000 credits)
2010 Lexus LF-A (350,000 credits)
2011 Mercedes SLS AMG (250,000 credits)
Level 37 Reward Choices1997 McLaren F1 GT (4,000,000 credits)
1998 Mercedes AMG Mercedes CLK GTR (1,200,000 credits)
1998 Nissan R390 (1,200,000 credits)
1999 Lamborghini Diablo GTR (200,000 credits)
Level 38 Reward Choices2010 BMW #79 Jeff Koons M3 GT2 Art Car (1,000,000 credits)
2011 Ferrari #62 Risi Competizione F458 Italia (1,000,000 credits, 2011.11 Speed DLC)
2010 Ferrari #83 Risi Competizione F430GT (1,000,000 credits)
2009 Ford #40 Robertson Racing Ford GT Mk7 (1,000,000 credits)
2011 Lamborghini #08 West Yokohama Gallardo LP560-4 (1,000,000 credits, 2012.01 Jalopnik DLC)
* 2010 Jaguar #33 RSR XKR GT (1,000,000 credits)
Level 39 Reward Choices2009 Bugatti Veyron 16.4 (1,400,000 credits)
2011 Koenigsegg Agera (1,400,000 credits, 2012.01 Launch DLC)
2010 SSC Ultimate Aero (1,000,000 credits)
2006 Koenigsegg CCX (550,000 credits)
2004 Saleen S7 (320,000 credits)
Level 40 Reward Choices2011 Ford #5 Ford Performance Racing FG Falcon (900,000 credits)
2011 Ford #19 Mother Energy Racing Team FG Falcon (900,000 credits)
2011 Holden #1 Toll Holden Racing Team Commodore VE (900,000 credits)
2011 Holden #11 Pepsi Max Crew Commodore VE (900,000 credits)
Level 41 Reward Choices2012 Pagani Huayra (1,800,000 credits, 2012.01 Jalopnik DLC)
2009 Pagani Zonda Cinque Roadster (1,500,000 credits)
2010 Joss JT1 (400,000 credits)
* 2010 Noble M600 (320,000 credits, 2012.05 VIP DLC)
2010 Gumpert Apollo S (320,000 credits)
2010 Mosler MT900S (320,000 credits)
Level 42 Reward Choices2011 Chevrolet #04 Chevrolet Racing Monte Carlo SS Stock Car (900,000 credits)
2011 Ford #05 Ford Racing Fusion Stock Car (900,000 credits)
Level 43 Reward Choices2011 Audi #04 Audi A4 Touring Car (1,200,000 credits)
2004 Audi #8 Audi ABT TT-R (1,200,000 credits)
2008 Mercedes Mercedes-AMG #4 C-Class Touring Car (1,200,000 credits)
2003 Opel #5 OPC TEAM PHOENIX Astra V8 (1,200,000 credits)
Level 44 Reward Choices1997 McLaren #43 Team BMW McLaren F1 GTR (1,500,000 credits)
1998 Nissan #32 Nissan R390 GT1 (1,500,000 credits)
2003 Saleen #2 Konrad Motorsport S7R (1,500,000 credits)
2000 Dodge #91 Viper Team Oreca GTS-R (1,100,000 credits)
2005 Maserati #15 JMB Racing MC12 (1,100,000 credits)
Level 45 Reward Choices2005 Honda #18 Takata Dome NSX (1,500,000 credits)
2010 Lexus #1 Petronas Tom's SC430 (1,500,000 credits)
2010 Nissan #12 Calsonic Impul GT-R (1,500,000 credits)
2003 Nissan #12 Calsonic Skyline (1,500,000 credits)
2005 Toyota #6 EXXON Superflo Supra (1,500,000 credits)
Level 46 Reward Choices2008 Aston Martin #009 Aston Martin Racing DBR9 (1,100,000 credits)
2006 Aston Martin #007 Aston Martin Racing DBR9 (1,100,000 credits)
2006 Chevrolet #4 Corvette Racing C6.R (1,100,000 credits)
2004 Chevrolet #3 Corvette Racing C5.R (1,100,000 credits)
Level 47 Reward Choices2011 Bugatti Veyron Super Sport (2,200,000 credits, 2012.05 VIP DLC)
2010 Pagani Zonda R (1,700,000 credits)
2008 Koenigsegg CCGT (1,500,000 credits)
2008 Mazda Furai (1,000,000 credits)
2011 Radical SR8 RX (300,000 credits)
Level 48 Reward Choices2006 Audi #2 Audi Sport North America R8 (2,200,000 credits)
2003 Bentley #7 Team Bentley Speed 8 (2,200,000 credits)
1999 BMW #15 BMW V12 LMR (2,200,000 credits)
2003 Panoz #11 JML Team Panoz LMP-01 (2,200,000 credits)
1999 Toyota #3 Toyota Motorsports GT-ONE TS020 (2,200,000 credits)
Level 49 Reward Choices2008 Acura #15 Lowe's Fernandez ARX-01b (2,000,000 credits)
2010 Chevrolet #99 Green Earth Team Gunnar Oreca FLM09 (2,000,000 credits)
2010 Mazda #16 Dyson Racing B09/86 (2,000,000 credits)
Level 50 Reward Choices* 2009 Acura #66 de Ferran Motorsports Jim Hall Tribute ARX-02a (2,500,000 credits)
2011 Aston Martin #6 Muscle Milk Aston Martin Lola (2,500,000 credits)
2011 Audi #2 Audi Sport Team Joest R15++ TDI (2,500,000 credits, 2011.11 Speed DLC)
2011 Audi #2 Audi Sport Team Joest R18 TDI (2,500,000 credits, 2012.02 ALMS DLC)
2009 Audi #2 Audi Sport Team Joest R15 TDI (2,500,000 credits)
2011 Puegeot #10 Matmut-Oreca 908 (2,500,000 credits)